In hybrid vehicles, energy storage components are known, such as special batteries, ultra capacitors, compressed materials, and flywheels for improving the fuel efficiency. This is particularly important for plug-in vehicles, because the battery has a limited energy capacity; any cost effective approach that can store and reuse the wasted energy must be utilized.
Hsu, U.S. Pat. No. 7,134,180 issued Nov. 14, 2006, describes a dual-rotor axial gap motor with a PM rotor (rotor with permanent magnets) and a second rotor for use in a hybrid vehicle. The second rotor is referred to as an uncluttered rotor because it couples only slip energy with the excitation coils due to the peripherally-oriented excitation coils.
There remains a need to provide a drive system for hybrid vehicles that will accomplish acceleration and braking while saving energy.